Bursting-strength tester for sheet material



Feb. 22,1927. 1,618,231 M. O. SCHUR BURSTING STRENGTH TESTER FOR SHEETMATERIAL Filed Nov. 9.71921 4 SheetsSheet1 1,618,231 M. O. SCHURBURSTING STRENGTH TESTER FOR SHEETMATERIAL Feb. 22, 1927.

Filed Nov. 9 1921 4 Sheets-Sheet 2 a'" 6/ i- IIIIIIIII I I I 62 i5 Feb.22,1927. 1,618,231

M. o. SCHUR BURSTING STRENGTH TESTER FOR SHEET MATERIAL Filed Nov. 9.'1921 4 sheets-sheets /I fig?! J! 1618,23] Feb. 22,1927. Q SCHUR BURSTINGSTRENGTH TESTER FOR SHEET MATERIAL Filed Nov 9. 1921 4 Sheets-ShetPatented Feb. 22, 1927.

MILTONO. SCI-FUR, OF BERLIN, NEW HAMPSHIRE, ASSIGNOR TO EROWN COMPANY,OF

BERLIN, NEW HAJLIPSHIRE,

A coRronATIoN or MAINE.

BURSTING-STRENGTH TESTER FOB SHEET MATERIAL.

Application filed November 9, 1921. Serial No. 514,044.

This invention relates to machines for testing the bursting strength ofsheetmaterial such as paper, pulp, fabric and the-like.

eter of 1 3 inches so that comparatively few tests are possible on agiven area of sheet.

When testing pulp also, this large area is found to give considerablevariation between individual tests. the material tending to tearirregularly. Moreover it is found that a considerable variation inreading may be produced by varying the rate at which pres-' sure isapplied to the diaphragm.

The present invention relates to a machine of the Mullen type. As thetest area of the Mullen machine is larger than desirable for testingpulp this invention contemplates a modified construction which requiresa much smaller test area. In order that this may be satisfactorilyaccomplished the diameter of the die through which the diaphragm isprojected in bursting the sheet is reduced. to substantially inch whilethe diaphragm itself is much'larger than this so that the area stretchedas the pulp bursts is much more. extended. This not only increases thelife of the diaphragm but also reduces the pressure required to stretchthe diaphragm alone to such a low figure compared to that required toburst the pulp that it becomes a negligible factor in the gage reading.

A furtherv feature relates to improved means for clamping the sheet inthe machine by which it is securely held. For this purpose at least oneof the clamping members is coated with an abrasive such as sandpaperwhich engages the surface of the sheet.

A further feature of the invention relates to power means applicableboth to the Mullen machine and the machine modified as above describedby which the increase of pressure on the diaphragm. is effected at auniform rate so that variability of readings due to variable ratesofapplying. the

pressure is eliminated. This mechanismalso eliminates the tiresome handoperation necessary withthe'Mullen tester as previously constructedwhich is an item of considerable importance wheremuch testingiisrequired;

A: further feature relates to a control mechanism by which connectionsbetween the pressure mechanism and the tester are ative on the startingof the pressure increasing mechanism and rendered inoperative as soon asthe sheet mater1al bursts.

Further objects and advantageous details 1 and combinations of partswill appear from a more complete description ofan embodiment shown inthe accompanying drawings in which i v Figure 1 is a front elevationpartly in section and partly broken away of the entire mechanism.

Figure 2 is a side elevation partly in section of the tester mechanism.1

Figure 3' is a top plan of the pressure applying mechanism.

Figure 4 is an end elevation partly broken away of the same mechanism.

Figure 5 device forming a part of the pressure applying mechanism.

automatically controlled. being made oper-' is a sectional detail of asafety I Figure 6 is a rear elevation of this mechaopening at its upperend into a recess 5 surrounded by an annular rim 6. Fined by oement tothe upper face of the rim 6 1s a rubber diaphragm shown at 7, the underface of this diaphragm being subjected to fluid pressure through theperforation 5 and the recess 5.

Positioned above the dlaphragm 1s a plate' 8 having a central dieopening9 substantially'smaller than the area. within the rim 6 andthrough which the diaphragm may be distended when subjected to pressureon its lower face. This plate 8 is of coniparatively thin material abovethe diaphragm but has a marginal thickened portion 10 which projectsdownwardly over the outer face of the table 3. The upper edge of theplate 8 has a marginal rabbet 11 to receive an inwardly directed flange12 on a clamping sleeve 13 which has threaded engagement at its lowerend with the outer face of the table 3. A rubber gasket ll'may bepositioned between the upper face of the table 3 and the marginalportion 8 of the plug 4 so that a tight sealing joint may be madebetween the hollow arm 2 and the diaphragm. by turning the sleeve 13 tobring the plate 8. downwardly.

The plate 8 is one of a pair of clamping plates between which thematerial to be tested is placed. The other clamping plate is shown at 15and is supported from a plurality of arched arms 16 which unite at theirupper ends in a collar 17 carried at the lower end of a plunger 18. Thisplunger 18 is vertically slidable in an arm 19 carried by the standard 1and projecting over the arm 2. The plunger 18 has a head 20 at its upperend and bearing beneath this head and surrounding the plunger is aspring 21 seated in a socket 22 in the arm 19. The

head 20 has a circular opening therein in which is journaled acylindrical head 23 carried by'an arm 24' which extends rear'wardlybetween a pair of spaced upwardly extending'jaws 25 carried by thearm 19 and the rear end of which rests on the upper end of a coil spring26 supported on a fixed boss 27 The plunger 18 may be depressed to clampthe sheet material between the plates 15 and 8 by a clamping lever 28pivoted at 29 between the jaws 25 and having a cam face 80 engaging theupper surface of the arm 24:. pring 21 is comparatively light and servesonly to lift the upper clamping plate when lever 28 is raised.

The'plate 15 has a die opening 33 having a dome-shaped upper end whichlimits the movement of the diaphragm when the sheet bursts andsubstantially mating the opening 9 of the plate 8, and its lower facesurrounding the die opening is coated with abrasive such as a ring ofsandpaper 150 to firmly grip the adjacent face of the sheet material.The two clamp surfaces are preferably ground together until absolutelyplane before the sandpaper is attached to one of them. Slidable in thisopening 33 is a pin 34, the lower end of which is impinged by thediaphragm when the sheet material bursts. This pin 34 is carried by alever 35. the outer end of which, as the pin is raised, impinges againsta spring contact 36 and forces it against a contact 37 on one of a pairof binding posts 38. These binding posts form part of a circuit designedto interrupt the supply of fluid pressure to the lower face of thediaphragm as will be later described.

Communicating with the arm 2 beneath the plug 1 is a pressure supplypipe 40 and fixed thereto is a maximum pressure gage of any suitabledescription as 411, apush pin 12 being shown by which this gage may bereturned to its Zero position after pressure is removed. 7

Referring now to Figure 1 at 50 is shown a cylinder in which a liquidmay be com pressed; From the upper end of this cylinder projects asupply pipe 51 connected on one side through a needle valve 52, whichthe opening for the passage of fluid may be constricted as desired,through a check valve 53 which prevents flow backwz'irdly toward thecylinder 50, to a three way valve 54' which is preferably of a balancednon-leakable type. This valve is shown in section in Figure 2 and isdesigned in one position to open communication from the pipe 51 throughthe needle and check valves to the pipe 10 leading to the lower side ofthe. diaphragm. In an other position of this valve the connection to thesupply cylinder 50 is blanked while the pipe 40 is connected to anoutlet pipe 55 which leads to a supply reservoir 56. From the lower endof this supply reservoir a pipe 57 leads through a check valve 58 to thepipe 51, this check valve permitting fluid to flow from the reservoir 56to the cylinder 50 but preventing flow in the reverse direction.

As shown the three way valve 5 1 is moved to cut off the connectionbetween the cylinder 50 and the diaphragm by means of a solenoid shownat 60. the core 61 of which acts against the arm 62 of they valve. Thissolenoid is in series with the binding post 38 above described so thatwhen the contact arm 36 bridges these posts the solenoid is energizedand the valve turned to cut off communication between the cylinder 50and.

the lower face of the diaphragm and to open communication between thelower face a L oi the diaphragm through the outlet pipe 55 to thereservoir 56. If desired the valve 54: might be operated by purelymechanical means being connected by links to the pin 341. The level ofthe liquid in the reservoir 56 is designed to be somewhat below thelevel of the diaphragm so that when con'-.

hollow of the thecylinder 50 and the testing mechanism in Cir order torender the flow of liquid therebetween very slow; During the building upof pressure-by the diaphragm the actual flow. of liquid 15 sllght sincethe movement of the-diaphragm is slight. lVhen the'sheet bursts,however, the volume for liquid in the tester increases suddenly and dueto the restricted flow through the needle valve the pressure thereinimmediately lowers since liquid may not flow sufficiently rapidly toimmediately fill the increased space. This construction has been foundof great importance, since-with an unrestricted flow a water hammerefiect may be produced from the sudden stopping of flow as soon as thedistention of the diaphragm is stopped after the bursting of the sheet,this giving a momentarily increased pressure giving an incorrect readingon the pressure dial 41. The small size of the perforations 5 throughthe plug d also aids in restricting the flow to the diaphragm.,

Means is provided by this invention for gradually and uniformlyincreasing the pressure on the fluid by power. This construction isshown more particularly in Figures land 3 to 7, inclusive. Referring tothese figures the cylinder 50 is seen to have movable therein a pistonOr plunger 601 which passes downwardly within a guide cylinder 611 onwhich the pressure cylinder 50 is supported. The lower end of thispiston'601 has preferably fixed thereon a guide collar or disk 621fitting within the guide member 611. The lower endof member 611 issupported on thetop of a hollow post 63 projecting upwardly from a base64:. Positioned within this post 63 is a vertically slidable rack bar65. This rack'bar is reducedat its upper end at 66 and surrounding thisreduced portion and bearing at one end against a shoulder 67 on the rackproduced by this reduced portion is a spring 68 which bears at itsopposite end against the under face of the disk 621. The reduced portion66 is formed hollow for the slidable reception of the head 69 of a rod70 which passes through a perforation 71 in the upper end of the rackbar, through the coil spring 68 and which is made fast at its upper endin the lower end of the piston plunger 601 at 72. It is evident that bypushing upwardly on the rack bar the force exerted on the spring 68 maybe increased, while ifby moving the rack bar downwardly the head 69impinges against the upper end of the rack bar, the piston plunger 601will be positively lowered. Bythislatter action it is insured that asupply of glycerine is drawn inwardly from the reservoir 56v as neededto supply losses due to leakage or otherwise inthe system so that theactual motion of the piston 601 will be through a very small amplitudeand willstart from the same position at eachactuation. I

The rack bar 65 is actuated by means of a pinion 75 fixed to a driveshaft 76. This shaft 76 is supported by, suitable bearings from thepedestal 6 1 and carries at one end a worm gear 77 with which meshes aworm 78 fixed to a horizontally arranged shaft 7 9. As shown the wormand gear are enclosed in a suitable casing 80. This shaft 79 has mountedthereon. a pair of loose pulleys 81 between which is a'fixed pulley 82.Adjacent to one of the loose pulleys 81 is also. fixed a-brake pulley83. Leading from the pulleys 81- and 82 and shiftable therebetween is apair of drive belts shown at 84 which pass over a common drive pulleynot shown. One of these belts is crossed so that when engaging the fixedpulley these belts will drive shaft 79 in opposite directions'. For thepurpose of shifting these belts between the fixed and loose pulleys-adouble belt shipper shown at 86 has been" provided. This shipper has twopairs of oppositely. extending shipping fingers 87 between which arepassed the belts 84 and it is fixed to a bar 88 slidably mounted inparallel relation to the shaft 79. For this purpose guidefingers- 89 areshown at one end thereof and ad acent the other 1s fixed a guide plate90. Adjacent to this guide plate the bar 88 has pivoted thereto a lever91 fulcrumed at'92 on a link 93 pivotedat 94 to a bracket 95 whichcarries one of the bearings for the shaft 79, this bracket being isupported from the base 64;. The lower end of the lever 91 is pivoted toa, link 96 extending to a, rocker arm 97. This rocker arm is fixed toarock shaft 98 which extends through the base 6tand which has fixed atits opposite end a double armed lever 99. Pivoted at the ends of thisle'veris a pair of treadles 100 which are maintained in parallelrelation by means of a link 101 pivoted at its opposite ends thereto andfulcrumed at the point 102 on a bracket 103 fixed to the base 64. ,7 Bythis means it seen that on depressing one-or the other of the treadles100 the belt shifter is moved to bring one or the other of the belts 84:into driving relation to the shaft 79 to actuatey.

the rack bar to increase or decrease the pressure exerted on the spring68 and conse-- quently the fluid pressure in'the cylinder 50. In orderthat the movement of the rack bar may be stopped automatically aftersufdevice to return the beltsto their inactive ,ficient movementin-either direction to acvcomplish its required functions a safetypositions on the loose pulleys has been provided. For this purpose thepost 63 is provided with. an extension or boss 105 on which is threadeda collar 106. This collar projects beyond the end of the boss and hasfixed thereto a key 10? slidable in a groove in the shaft 76. By thismeans the collar 106 must rotate with the shaft 76 but is moved axiallyof the boss 105 during such rotation. This collar 106 has fixed theretoa circular flange 108 which carries on opposite sides thereof a pair ofarms 109 and 110. These arms are offset at their ends as shown moreparticularly in Figure 7, and are positioned one on either side of thebelt shifter bar 88. On either side of this bar 88 are a pair offrustro-eonical rollers 111 and 112 which are journaled on a bolt orstud 113 passing through the bar, Referring to Figure 7 it 1s noted thatthe arm 109 is in position to engage the roll 113 on rotation of theshaft 76 in a direction to move the arm 109 to the left, it beingdesigned thatin such position of the parts the bar 88 will be moved toshift the belts to stop the rotation of the shaft in this direc tion.Itis also tobe noted that as a reverse direction of rotation of theshaft 76 brings the arm 110 to the right, the end of this arm passesbeyond the end of the roll 112. On a succeeding complete rotation of theshaft 76, however, the arm 110 is moved inwardly in position to contactthe roll 112 due to the threaded engagement of the collar 106 with theboss 105 and it then shifts the rod 88 to the right to throw the drivingbelt for this direction of rotation on to the loose pulley. The arm 109is now beyond the end of roll 113 so that on the first complete rotationof shaft 76 in the reverse direction it fails to move the bar 88 but onthe next rotation it strikes the roll and shifts the belts to stopfurther rotation of the shaft. It is therefore seen that after tworevolutions of the.

shaft 7 6 in either direction the power for rotating the shaft in thatdirection is cut bracket 90 in position to be contacted and raised by acam plate 121 fixed to the bar 88. By this means when the bar 88 isshifted in either direction .to bring the previously active belt on totheloose pulley'th-e roll 120 is raised and the brake band 115 tightenedabout pulley 83 to stop the mechanism.

If desired the valve 54 may be actuated Thebearing 89 for the bar 88carries a post 132 of insulating material which carr1es a,

contact element 133. A bracket 134 extends outwardly from the post132and has pivoted at its extremity a lever 135 also of insulatingmaterial. Fixed to the upper end of'this lever is a spring arm 136carrying a contact element 137 adapted to impinge against element 133 onrockingthe lower end of lever 135 away from post 132. The closing ofthese contacts closes the electric circuit through the solenoid 130.These contacts are normally held apart by a spring 138 urging the lowerend of lever 135 toward the post 132. To this end, however, is pivoted alatch member 139 having a portion 140 arranged to contact the side ofthis lever to limit its upward pivotal movement relative thereto. Theend of bar 88 has fixed thereto'a plate 141, which. as the bar moves toshift the belts to start the operation of the pressure mechanism bypressure on the right hand treadle of Figure 1, contacts the lower endof member 139, rocks itnpwardly until the portion 1 10 contacts lever135 and then turns this lever to establish contact between elements 133and 137. The plate 141 then slips from beneath member139 and thecontacts are immediately separated by the spring 138. On return of bar88, the plate 141 passes beneath member 139, rocking it idly about itspivotal connection with the lever 135 sufficiently to permit this actionwithout affecting the contacts.

The sheet to be tested is inserted between the plates '15 and 8, thelever 28 being in raised position as shown in Figure 2, whereupon thelever 28 is pushed downwardly to bring the plate 15 against the uppersurface of the sheet. The right hand treadle 100 is then depressed,which as above described, through the solenoid 130 actuates the valve 54to connect the pressure cylinder 50 to the lower side of the diaphragm.The pressure within the cylinder 50 is then gradually and uniformlyincreased as the rack bar 65 is moved upwardly until the sheet burstsand the diaphragm stretches within the die opening 33. hen this takesplace the electrical coi'mections are closed through the solenoid 60whereupon this solenoid is actuated to automatically to connect thepressure cyl- 7 inder 50 with the lower side. of the die-- shut off theconnection to the diaphragm 7 attached thereto over an areasubstantially reservoir 56. The left hand treadle'100 as shown in Figure1 is then depressed to return'the rack bar to its initial position torelieve the pressure on the hydraulic system and'to fill the cylinder 50from the reservoir. The apparatus is then in position for repetition ofthe same cycle. The pressure at which'the bursting of the sheet hastaken place is then read directly from the gage 41 which may be returnedto zero by pressure on the release button42; Overtravel of the rack ineither direction is prevented by the arms'109 and 110 contacting andmoving the bar 88 to its neutral position. f

Having thusdescribed an embodiment of this invention it should beevident to those skilled in the art that many changes and modificationsmight be made therein without departing from its spirit or scope asdefined by the appended claims.

I claim: v 1; A device of the class described comprising a pair ofplates between which a sheet may be clamped, one of said platesstantially larger than that of said opening,

and means for subjecting said diaphragm to fluid pressure to project itthrough said opening to burst thesheet.

2. A device of the class described comprising a lower clamping platehaving an opening therethrough, a perforated plug positioned below saidplate, a diaphragm fixed to the upper face of said plug and unlargerthan the opening of said plate, an upper clamping plate having anopening in registry with the opening'of said lower plate and by which asheet may be clamped against said lower plate, and means for supplyingfluid pressure to the lower side of said diappragm through theperforation in said u p 3. A device of the class described comprising alower clamping plate having an opening therethrough, a perforated plugpositioned below said plate, a diaphragm fixed to the upper face of saidplug and unattached thereto over an area substantially larger than theopening of said plate, a collar for retaining said lower clamping plateagainst the upper face of said plug,

an upper clamping plate having an opening in registry with the openingof said lower plate and by which a sheet may be clamped against saidlower plate, and means for supplying fluid pressure to the lower side ofsaid diaphragrnthrough the perforation in said plug. 7

.4. A d'evice ofthe class described com prising means .for applyingpressure against one side of sheet material tending to burst the same,and means for increasing the prisingmeans'for holding a sheet, fluidpressure mechanism actuableto burst the sheet, a

on the bursting of said sheet for controlling pressure insuringsuchincrease at'a uniform rate. 7 i v v 5. A device of the classdescribed com-, prising means for applying pressure against one side ofsheet material tending to burst the. same, and power means acting toincrease the pressureat a uniform rate. '6.'A deviceof the classdescribed comprising plates between which sheet material may be clamped,said plates havin registering openings therethrough, a. iaphragmsubjected on one side to fluid pressure and engaging one side of thesheet material over the area defined by the opening in one of saidplates, and means for increasing the pressure on said diaphragm at a"uniform rate until said diaphragm bursts the sheet, a material. 'i 1 I7. In a device ofthe class described comfluid pressure supply adapted tobe placed in communication with said mechanism, means acting to increasethe pressure in said supply at a constant rate," and means actu- 9 atedon'the bursting of said sheet to disconnect said supply from saidmechanism.

8. A device of the class describedcompris' iug means for holding asheet, pressure responsive mechanism ,acting to burst the sheet, asource of pressure, a valve betweensaid source and mechanism, magneticmeansfor fclosing said valve, and a switch" actuated saidmagnetic'means.

j 9. A device of the class described comprising in combination, meansfor holding a sheet, pressure responsive :mechanism actuable to burstthe sheet, a fluid pressure supply, means'for increasing the pressure offluid in said supply, a valve controlling the communication between saidsupply and mechanism, means actuated on the initiation of said pressureincreasing means for opentuating said valve, a switch for controllingthe opening of said valve actuated on the initiation of said pressureincreasing means,

and a switch for controlling the closing of said valve actuated on thebursting of said sheet.

11. A device of the class described comprising means for holding asheet, fluid pres sure mechanism actuable to burst the sheet, a fluidpressure supply, means including a, constricted portion for transmittingfluid mg said valve," and means "acting on the 110 pressure from saidsupply to said mechanism, means for increasing the pressure of saidsupply, and means actuated on the prising in combination, means forholding a sheet, fluid pressure mechanism actuable to burst the sheet, afluid pressure supply adapted to be placed in communication with saidmechanism, means to increase the pressure of said supply, means to closethe communication between said supply and mechanism after the sheetbursts, and a means re stricting the flow of fluid from said supply tosaid mechanism to prevent a momentary increase of pressure in saidmechanism after the bursting of said sheet. 13. A device of the classdescribed comprising in combination, means for-holdinga sheet, fluidpressure mechanism for bursting the sheet, a fluid pressure supplyadapted to be placed in communication with said mechanism, means forincreasing the pressure offluid in said supply, a fluid reservoir, andmeans acting after the bursting of said sheet for closing offcommunication from said supply to said mechanism and openingcommunication from said mechanism to said reservoir. I 7

14:. A device of the class described comprising in combination,means'for holding a sheet, fluid pressure mechanism for burst- !ing thesheet, a fluid pressure supply adapted to be placed in communicationwith said mechanism, means for increasing the pressure of fluid in saidsupply, a fluid reservoir,

and means acting after the bursting of said sheet for closing offcommunication from said supply to said mechanism and openingcommunication from said mechanism to said reservoir, the level of fluidin said reservoir being below said diaphragm to cause said diaphragm tobe drawn away from said sheet when said mechanism is connected to saidreservoir.

15. A device of the class described comprising in combination, a fluidpressure cylinder, a piston movable therein, a spring bearing on saidpiston, fluid pressure mechanism for testing material in communicationwith said cylinder, and means acting to increase the pressure exerted bysaid spring at a determined rate to correspondingly increase the fluidpressure in said mechanism.

16. In a device of the class described, a fluid pressure applyingmechanismcomprising a fluid pressure cylinder, a piston in saidcylinder, a spring acting on said piston, and power means acting toincrease the pressure exerted by said spring at a predetermined uniformrate.

17. In a device of the class described, a fluid pressure applyingmechanism comprising a fluid pressure cylinder, a piston IHOV-spondingly increase the pressure of fluid in i said cylinder.

18. In a device of the class described, a fluid pressure container,powermeans acting to increase the pressure in said container at apredetermined uniform rate, and means acting a definite time after thestartin thereof for stopping the operation of said power means. Y j r19. In a device of the class described,'comprising afluid pressurecylinder, apiston movable in said cylinder, a spring bearing at one endon said piston, abar engaging the opposite'end of said spring, a shaft,connections from said shaft to said bar whereby rotation of said shaftin opposite directions moves said bar toward and from said cylinder toincrease or decrease-the pressureof fluid therein respectively, meansfor rotating said shaft, and means for reversing the direction ofrotation of said shaft. 7 i

20. In a device of the class described, a fluid pressure applyingmechanism comprising a fluid pressure cylinder, a piston in saidcylinder, a bar reciprocable in line with the axis of said piston, aspring interposed between said bar and piston, a shaft, a tight pulleyand a pairof loose pulleys on said shaft, a source of power, a pair ofbelts from said source to said pulleys arranged to drive in reversedirectlons, means for shifting sa d belts between said tight andloose-pulleys to rotate said shaftv in either direction at will, andconnections acting to move said bar toward and from said piston onreverse directions of rotation of said shaft.

21. In a device of the class described, a fluid pressure applyingmechanism comprising a fluid pressure cylinder, a piston in saidcylinder, a bar reciprocable in line with the axis of said piston, aspring interposed between said bar and piston, a shaft,a tight pulleyand a pair of loose pulleyson'said shaft, a source of power, a pair ofbelts from said source to said pulleys arranged to drive in reversedirections, means for shifting said beltsbetween said tight and loosepulleys to rotate said shaft in either direction at Wlll, connectionsacting to move said bar toward and from said piston onreverse directionsof rotation of said shaft, andv means to-shift said belts to stop therotation of said shaft after a definite extent of rotation thereof ineither direction.

22. A device of the class described comprising a pair of annular platesfor clamping asheet, means for bursting the'sheet through one of saidplates, and an abradant carried by one of saidplates in engagement withthe and e dome shapedeleinent on the opposite side of said plates fromsaid diaphragm to limit the movement'of said diaphragm When 10 i thesheet bursts. V v e In testimony whereof I have afiixed' my signature. t

' I MILTON O. SCHUR.

